The Blue Beast Blues

I apologize for the length of this. But here is how this all started. I’ll try to include everything even those I think are irrelevant.

‘94 Z28 6spd. – 75K mi.

I replaced the OptiSpark complete because it was running really lousy, new plugs & wires. New MSD coil. Modified the OptiSpark with the GM vacuum hose assembly, new Hypertech 160 deg. thermostat. Water pump was in good shape so did not replace.

Probably irrelevant info:
I changed the oil and filter, power steering fluid, fuel filter, air filter. Put new coolant in when I reassembled, 50/50 with distilled water.

Here are the current repeatable problem/symptoms, none of which happened before the above maintenance:

When I start it it takes a few seconds to crank and finally starts. When it does start the SES light and fans come on and run continuously. The AC compressor also will not turn on. So when I go to start it I think that it checks all the cylinders to see if it has spark, fuel etc. and then says it is OK to start and then starts. If I turn the key all the way off and wait it will take the same time to start, but if I just turn the key to the accessory position for a few seconds it will start a little sooner depending on how long I have it off. When I pull the fuse to clear the faults in the PCM and then start, it still starts the same, i.e. slow, then the SES light comes on about 2 seconds after it starts and then about 7 seconds later the fans come on.

I have an old, simple SunPro code reader [that just jumps the pins], but I can’t get it to give any codes. The fans will also run when I plug in the reader. AutoZone said that if I can’t get any codes with what I have then they would not be able to do anything else to read it.

I know from searching around that the fans come on when you jump the pins with a reader and that they also come on when the SES light is on. But since I cannot get it to give me any codes with my little “pin jumper” I don’t know if anything is actually related to a bigger problem or separate issues. I have also heard people say just to leave the fans run, but that is not solving any of the problems.

When it does start it runs better then it ever did…. like new! It is absolutely great except for this puzzling issue. Drivability is absolutely fantastic all the way thru the RPM range in every gear.

Things I have checked in a futile effort to fix the problem(s):
Both Coolant temp sensors, compared operation at cold and hot to new ones, same.
All Relays except Fuel pump relay (but fuel pump turns on and primes fuel rail) to the stop point.
EGR Valve (applied vacuum works fine)

Is there anyone who has had these problems or heard of anything like this that can give me some assistance? I would really appreciate it. If jumping the pins with the reader can’t give me any codes will a shop with a computer be able to get any info from the PCM?

 

You must use a scanner to retrieve codes. Jumping the pins will not work on a 1994 or later.

 

The check valve in your fuel pump may be going out. The fuel pump is not holding pressure like it should when the car is turned off. It causes the motor to have to crank over a few more times before it builds enough pressure to start. Out of curiosity. How long did it take you to complete all the work you did on the car? How much fuel was in the tank while the work was being performed? IIRC the pressure valve is like a rubber balloon. If the car sits long enough with hardly any fuel in the tank, the rubber valve will dry rot and will not hold pressure. My car was doing the same thing back in the day. Eventually I changed the fuel pump and my problem was solved. By turning the key to the on position before you start it, you are allowing the system to build pressure before you crank it, that is probably why it starts faster if you turn the key a few times before you go to start it. I dont remember ever having an SES light tho. But its worth a shot for you to give this a try. Hope this helps you a little bit. Peace.